Automatic telephone system



F. J. TRUBY.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED m1. :5. 1918.

1,343,989. v Patented June 22,1920.

UNITED STATES,

PATEN oFFicE.

FRANKLIN J. TRUBY,-OF CHICAGO, ILLINOIS, 'ASS IGNOR TOAUTOlVIATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed a ru s, lsis seriai' No. 228,536.

To all wlwm'it may concern: i

Be. it known that I, FRANKLIN J. TRUBY,

' a citizen of the United States of America,

connect with an idle trunk line.

ajpredetermined number of impulses over and a resident of Chicago, Cook county, and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates in general to switches for use in an automatic telephone system j and more specifically to an improved line switch or switching mechanism which is especially adapted for use as an individual line switch, that is, as a switch individual to each subscribers'line which operates automaticallywhen the receiver of a calling:

line is lifted to automatically select and I have shown my improved line switch at C in the drawings as individual to the line of substation A and as having access to a plurality of trunk lines, only one of which is shown leading to a plurality of connected switches similar to that shown at H, The substation 13 and its line switch G are similar in all respects to the substation A and its line switch C. Among the objects of my invention is to provide a line switch of this general type which is simple in construction and operates in a novel and efiicientmanner to perform the desired trunking operations.

Having described the general features and objects of my invention, I will describe the operation 0 my system in detail by referring to the accompanying drawings. 1

The substation A comprises the usual transmitter 2, receiver 8, ringer 4, switch hook 5, for controlling the switch hook springs, and a calling device CD of any well known type comprising a pair of springs.

which may be opened and closed to deliver the two sides of aline in series. The line switch C is of a well known rotary type of line switch having a rotary operating mag net 6 which interrupts its own circuit to advance the wipers from the position in which they were left bythe last call to an idle trunk, and a marginal slow acting switching relay 7 which operateswhen such idle line is found to switch the connection through tothe idle trunk.

. The connector switch His of a well known Keith Erickson type in which the operation iscontrolled over the two sides of a" calling line in series and comprises a line relay 8, a slow release relay 9, slow series relay 10, busy relay 11, back bridge relay 12, ring cut off relay 18, wiper cut on relay 14, vertical magnet 15, rotary magnet 16, a release magnet 17, and the private magnet 18 for controlling the side switch. a

When the receiver at substation A is re moved from'the hook to initiate a call, a circuit is closed from ground through springs 19 and 20, to and through the equipment of substation A, andback through springs 21, lower winding of relay 7, and through the winding of magnetfi and into sprmgs 22 to battery. The relay 7 does not energize as quickly as magnet 6 'and over this circuit, magnet 6. is energized only strong enough to close its springs 23,24 and 25 and does not'open its interrupter springs 22. As soon as the springs 24 makecontact,

and assuming that the trunk line upon which the wipers 26, 27 and '28 have been left standing is busy, then a ground will be .suppliedflfrom some occupying switch (not shown) to the private wiper28 and from thence through springs 24 to the junction point between relay 7 and magnet 6 in the above traced series circuit. It'will be seen therefore that as soon as springs 24 close, they short circuit the lower winding of relay 7 and cause the rotary magnet to energize over this last circuit from ground direct.

Magnet 6 will therefore energize to step the wipers onto the next succeeding set of contacts, and if this set is busy magnet 6 will again energize to give the wipers another step and so on, the interrupter springs opening the circuit of magnet 6 at each energization thereof. As soon as an idle trunk line is reached theclosure of springs 24 will no longer short circuit the winding of relay 7 which will therefore operate the lower light armatureto open the springs 19 and 20 and springs 21 and to close a circuit from ground through springs 19 and 29 and throughsprings 25 to the upper windingof relay 7 The two windings of relay-7 being energized are strong enough to pull up the heavier armature of said relay to operate the springs 30 to 33 inclusive, and the upper winding being only strong enough to hold said heavy arm attracted after beingfirst pulled up.

It will be understoodthatalthough We have represented relays 6 and 7 as each having a plurality of armatures, yet only one pair of armatures may be used, a heavy armature controlling the springs which are shown heavy in the drawing and a light armature controlling the rest of the springs which are shown light in thedrawing.

The initial energizing circuit of relay 7 and magnet G is now held open and the relay 7 is held energized by the current in its upper winding only, springs 34 are also opened to open, the circuit of. magnet 6 whichwas closed by the springs 23 of magne (3 and by spring 19 of relay 7 and its front contact, thereby preventing any circuit being closed through the magnet 6 after it has once fallen back. The relay 6 remains energized long enough to hold the circuit of the upper winding closed until ground is fed back from the selector or connector seized, that is, the springs 83 are the last to break contact.

The closure of springs 30 and extends the line circuit to theline relay 8 of connector H over the wipers 26 and27 causing said relay to energize in series with theline to close a circuit for the release relay 9. Relay 9, upon energizing, closes a circuit from ground through springs 3st, private wiper 28, springs 31, and upper winding of relay 7 to battery.

At this time the calling subscriber operates his calling device CD in accordance vith the digits of the called ninnber to operate the switch H. As the relay 8 deenergizes in response to the lirst digit the circuit of magnet 15 is openedand closed a number of times in series with the relay 10 v to step the wipers to a desired levelof con-' tacts. During the operation of magnetjlfi, relay 10 remains energized and maintains a circuit for the private magnet 18 from ground through springs and 36 and said magnet to battery. After the impulses cease relay 10 will dei nergize and open the circuit of magnet 18. The magnet 18 at this time causes the side switch wipers S7 and 38 to step to .second position to prepare a circuit for the rotary magnet 16 and the busy relay 11. lVhen the line relay responds to the next digit the rotary magnet 16 is'operated to step the wipers around to the desired line contacts and relay 10 again controls the private magnet 18 to cause the wipers 37 and 38 to step to third position if the called line is idle. If the line is busy, however, a

. ground will be present on the contact which the wiper, 89 tests and a circuit will be closed from said ground through wiper 39, side switch wiper 38 (in second position) springs 42 and 43, relay l1, springs 44 and 36 and magnet 18 to battery. The relay 18 will not be deenergized to step the side switch wipers and relay 11 will operate to lock itself and magnet 18 to ground through the off normal springs, open-the circuit of the rotary magnet, and connect the busy machine M to the called line to indicate that the called line is busy.

If the called line had been idle no circuit would be closed for relay 11 andmagnet 18 and the side switch would immediately pass to third position. As the wipers 37 and 38 reach third position a circuit is closed for the relay 14" which operates to connectthe wipers 40 and 41 to the springs of relay 1? and thence to ringing current. The interrupting device R alternately supplies generator current and booster battery current to the called. line and through one winding of relay 13 to battery. As soon therefore as the called subscriber answers the relay '13 will energize to disconnect the ringing leads from the called line and to connect the back bridge coil 12 across to supply talking current.

As soon as the side switch 7 wiper 3S reached third position a circuit. was closed from ground through said Wiper 38, private wiper 39, and upper winding of relay? of the individual switch C tocause said relay 7 to pull up its light armature to disconnect the ground G from the talking circuit the called line and prevent any operation oil-magnet (S J andrelay' are both marginal in action and each has a heavy and a light armature. Although I have not shown the light and heavy armatures of each coil it will" be understood that the energization of both windings of the relay 7- operate all the springs while either winding alone operates only those springs shown below said coil. Also the magnet 6 when energized in series with the winding of relay 7 will operate only its upper springs 23, 24 and'25, while when energized direct it will operate the interrupter springs shown below the coil at 22. y g

\Vhat I claim as my invention .is:

1. In a telephone, system, an automatic switch, an operating magnet for said switch, a relay for controlling said magnet, means for closing a circuit including the two sides of a calling line in series through said relay and magnet in series, means controlled directly by said magnet for maintaining said relay short circuited, and means controlled by said relay for rendering said magnet inoperative.

2. In a telephone system, an automatic switch, a marginal magnet for causing said switch to rotate to select idle trunk lines, a pair of armatures for said magnet, means for energizing said magnet to attract only one of said armatures when the switch is seized, means for energizing said magnet to attract the other of said armatures if the tested trunk is busy and means for rendering said magnet inoperative as to both armatures when an idle trunk line is found.

3. In a telephone system, an automatic switch, a motor magnet and a switching relay for said switch, means'for closing a circuit for said relay and magnet in series when the switch is seized for use, a pair of armatures for the relay and a pair for the magnet, said magnet energized over said circuit to attract only one of its armatures, a circuit closed by said one armature for short circuiting the winding of said relay and causing said magnet to attract its other armature, means controlled by said other armature for opening said second circuit, said relay energized when the short circuit is opened to attract only one of its armatures and means controlled by said one armature of the relay for causing said relay to attract its other armature.

at. In a telephone system, an automatic switch, a motor magnet and a switching relay for said switch, means for closing a circuit for said relay andmagnet in series when the switch is seized for use, a pair of armatures for the relay and a pair for the magnet, said magnet energized over said circuit to attract only one of its armatures, a circuit closed by said one armature for short circuiting the winding of said relay and causing said magnet to attract its other armature, means controlled by said other armature for opening said second circuit, said relay energized when the short circuit is opened to attract only one of its arma-,

tures, means controlled by said one armature of the relay for causing said relay to attract its other armature, and means controlled by the attraction of the other armation of said switch, a pair of windings for said relay, a pair'of armatures for said relay, means controlled by either of said windings alone for attracting only one of said armatures, means controlled by the energization of both windings for attracting the other armature, means controlled by either winding alone for holding said other armature attracted, and means controlled by the attraction of said other armature for rendering said operating magnet inoperative to thereby prevent further operation of the switch.

6. In a telephone system, a subscribers line, a switch individual to said line, an operating magnet and a switching relay for said switch, means for closing a circuit including the two sides of said subscribers line in series and said relay and magnet to cause said switch to operate to test trunk lines, said magnet operating in one manner when a busy trunk is tested to continue the operation of the switch and render said relay inoperative and operating in another manner when a trunk is idle to cause said relay to energize and lock energized, and

means controlled by the energization of said a relay for opening the circuit of said magnet. 7. In a telephone system, a subscribers line, an automatic switch for said line, a relay for controlling the operation of said switch, a first and second winding and a pair of armatures for said relay, means for energizing said relay through said first winding to attract only one of said armatures when a call isinitiated by said line, means for energizing both windings to attract both armatures when a connection is extended, and means for energizing the second of said windings when the line is called to attract only one of said armatures.

Signed by me at Chicago, Cook county, Illinois, this 11th day of April, 1918.

FRANKLIN J. TRUBY. 

